US4425701A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Methods of making magnetic recording heads
Assignee: Panasonic Holdings Corp
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Filing: 1981-10-09
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Granted: 1984-01-17
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Expires: 2001-10-09
Abstract
Abstract A method for making magnetic recording heads suitable for mass production with high accuracy. The track width tw or w of the head core is defined by a photolithographic etching method. First, larger grooves are formed by mechanical machining or electrolytic etching to form an outline of the pole piece parts, and then further smaller and shallower grooves are formed with very high accuracy by an etching process, such as electrolytic etching, sputter etching or ion etching at the edges of the first grooves. Thus, the track width of the head core is accurately determined by means of a photolithographic process.
Inventors
- 👤 Ken Takahashi
- 👤 Hiroshi Youda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 12:18
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/187; G11B5/1871; G11B5/1272; G11B5/133; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/4902; Y10T29/49021; Y10T29/49032; Y10T29/49036; Y10T29/49048; Y10T29/49052
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
186 words
A method of making magnetic recording heads having a predetermined track width associated therewith, comprising the steps of: forming first grooves on a face of a ferromagnetic substrate disposed substantially parallel to each other, spaced apart by a distance wider than said track width, by forming a first mask and a second mask which is broader than said first mask, covers said first mask and is removable separately from said first mask, and carrying out a first etching of said substrate by using said second mask as an etching mask; subsequently forming by photolithographic etching, second substantially parallel grooves having a depth shallower than that of said first grooves, disposed parallel to and connecting to said first grooves at the edges thereof, by selectively removing said second mask while retaining said first mask, and carrying out a second etching to form said second substantially parallel grooves using said first mask as an etching mask, said second grooves defining track width by the distance inbetween; cutting the ferromagnetic substrate into a predetermined number of units; and assembling a core by utilizing at least one of said units.
Claim 2
Independent Claim
186 words
A method of making magnetic recording heads having a predetermined track width associated therewith, comprising the steps of: forming first grooves on a face of a ferromagnetic substrate disposed substantially parallel to each other, spaced apart by a distance wider than said track width, by forming a first mask and a second mask which is broader than said first mask, covers said first mask and is removable separately from said first mask, and carrying out a first etching of said substrate by using said second mask as an etching mask; subsequently forming by photolithographic etching, second substantially parallel grooves having a depth shallower than that of said first grooves, disposed parallel to and connecting to said first grooves at the edges thereof, by selectively removing said second mask while retaining said first mask, and carrying out a second etching to form said second substantially parallel grooves using said first mask as an etching mask, said second grooves defining track width by the distance inbetween; cutting the ferromagnetic substrate into a predetermined number of units; and assembling a core by utilizing at least one of said units.
Claim 3
Dependent Claim
18 words
A method of making magnetic recording heads in accordance with claim 1, wherein said substrate is a plate.
Claim 4
Dependent Claim
40 words
A method of making magnetic recording heads in accordance with claim 1 which further comprises a step of filling said first grooves with non-magnetic substance, followed by grinding and polishing said face, prior to said subsequent step of photolithographic etching.
Claim 5
Dependent Claim
19 words
A method of making magnetic recording heads in accordance with claim 1, wherein said plate is of a ferrite.
Claim 6
Dependent Claim
36 words
A method of making magnetic recording heads in accordance with claim 1, wherein a gap spacer film is applied on at least the portion of said face to become a recording gap, prior to said cutting.
Claim 7
Dependent Claim
36 words
A method of making magnetic recording heads in accordance with claim 1 wherein said assembling step comprises the step of assembling two of said units with the faces thereof opposed spaced apart by a gap therebetween.
Claim 8
Dependent Claim
18 words
A method of making magnetic recording heads in accordance with claim 6, wherein said substrate is a plate.
Claim 9
Dependent Claim
40 words
A method of making magnetic recording heads in accordance with claim 6 which further comprises a step of filling said first grooves with non-magnetic substance, followed by grinding and polishing said face, prior to said subsequent step of photolithographic etching.
Claim 10
Dependent Claim
19 words
A method of making magnetic recording heads in accordance with claim 6, wherein said plate is of a ferrite.
Claim 11
Dependent Claim
36 words
A method of making magnetic recording heads in accordance with claim 6, wherein a gap spacer film is applied on at least the portion of said face to become a recording gap, prior to said cutting.
Claim 12
Independent Claim
188 words
A method of making magnetic recording heads having a predetermined track width associated therewith, comprising the steps of: forming first grooves on a face of a ferromagnetic substrate disposed substantially parallel to each other, spaced apart by a distance wider than said track width; subsequently forming by photolithographic etching, second substantially parallel grooves having a depth shallower than that of said first grooves, disposed parallel to and connecting to said first grooves at the edges thereof, said photographic etching comprising the steps of forming a first mask and forming a second mask which is broader than said first mask, covers said first mask and is removable separately from said first mask, a first etching to form deeper second groove by using said second mask as an etching mask, selectively removing said second mask while retaining said first mask, and a second etching to form a shallower third groove using said second mask as an etching mask, said third grooves defining track width by the distance inbetween; cutting the ferromagnetic substrate into a predetermined number of units; and assembling a core by utilizing at least one of said units.
Claim 13
Independent Claim
188 words
A method of making magnetic recording heads having a predetermined track width associated therewith, comprising the steps of: forming first grooves on a face of a ferromagnetic substrate disposed substantially parallel to each other, spaced apart by a distance wider than said track width; subsequently forming by photolithographic etching, second substantially parallel grooves having a depth shallower than that of said first grooves, disposed parallel to and connecting to said first grooves at the edges thereof, said photographic etching comprising the steps of forming a first mask and forming a second mask which is broader than said first mask, covers said first mask and is removable separately from said first mask, a first etching to form deeper second groove by using said second mask as an etching mask, selectively removing said second mask while retaining said first mask, and a second etching to form a shallower third groove using said second mask as an etching mask, said third grooves defining track width by the distance inbetween; cutting the ferromagnetic substrate into a predetermined number of units; and assembling a core by utilizing at least one of said units.
Claim 14
Dependent Claim
18 words
A method of making magnetic recording heads in accordance with claim 11, wherein said substrate is a plate.
Claim 15
Dependent Claim
40 words
A method of making magnetic recording heads in accordance with claim 11 which further comprises a step of filling said first grooves with non-magnetic substance, followed by grinding and polishing said face, prior to said subsequent step of photolithographic etching.
Claim 16
Dependent Claim
19 words
A method of making magnetic recording heads in accordance with claim 11, wherein said plate is of a ferrite.
Claim 17
Dependent Claim
20 words
A method of making magnetic recording heads in accordance with claim 11, wherein said first grooves are formed by machining.
Claim 18
Dependent Claim
36 words
A method of making magnetic recording heads in accordance with claim 11, wherein a gap spacer film is applied on at least the portion of said face to become a recording gap, prior to said cutting.
Claim 19
Dependent Claim
29 words
The method of claim 11 wherein said assembling step comprises the step of assembling two of said units with the faces thereof opposed spaced apart by a gap therebetween.
Claim 20
Dependent Claim
18 words
A method of making magnetic recording heads in accordance with claim 17, wherein said substrate is a plate.
Claim 21
Dependent Claim
40 words
A method of making magnetic recording heads in accordance with claim 17 which further comprises a step of filling said first grooves with non-magnetic substance, followed by grinding and polishing said face, prior to said subsequent step of photolithographic etching.
Claim 22
Dependent Claim
19 words
A method of making magnetic recording heads in accordance with claim 17, wherein said plate is of a ferrite.
Claim 23
Dependent Claim
20 words
A method of making magnetic recording heads in accordance with claim 18, wherein said first grooves are formed by machining.
Claim 24
Dependent Claim
36 words
A method of making magnetic recording heads in accordance with claim 17, wherein a gap spacer film is applied on at least the portion of said face to become a recording gap, prior to said cutting.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-01-16 | 1987-07-18 | 1988-01-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-01-16 | 1991-07-18 | 1992-01-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-01-16 | 1995-07-18 | 1996-01-17 | $7700.00 | Window Closed / Lapsed |